It is known that heat curable workable foundry shapes can be prepared by the so-called "hot box" process. This process involves injecting a mixture of a foundry aggregate containing an acid-generating curing catalyst and a thermosetting resin into a heated corebox where it is allowed to harden into a workable foundry shape, which is then removed from the corebox. Curing according to this process takes place in an acidic medium. The use of this process can, depending upon the choice of catalyst and resin, cause the formation of undesirable smoke and fumes due to the generation of free phenol and free formaldehyde, as well as the generation of significant amounts of nitrogen which can result in the formation of casting defects (pinholes) when metal castings are prepared. This process also requires that the acid-generating curing catalyst and thermosetting resin be mixed with the aggregate as separate components.